<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // && 且
        var a=true;
        var b=false;
        console.log(a&&b);
        var a=true;
        var b=true;
        console.log(a&&b);
        // 或||
        var a=true;
        var  b=false;
        console.log(a||b);
        // ! 取反 会自动转化为布尔值类型
        var a=10;
        console.log(!a);
    </script>
</body>
</html>